1. Field of the Disclosure
This disclosure generally relates to a human machine interface device and, more particularly, to an optical navigation device and a locus smoothing method thereof capable of increasing locus smoothness.
2. Description of the Related Art
Traditionally, the optical mouse is one of the peripheral devices for interacting with the computer system having a display screen. An optical mouse generally includes a light source, an image sensor and a processing unit. The light source emits light to a working surface. The image sensor receives reflected light from the working surface and successively outputs image frames. The processing unit calculates a displacement of the optical mouse with respect to the working surface according to the image frames and sends the displacement to a computer system with a report rate for corresponding control.
However, as the image frames captured by the image sensor may contain noise, the noise will reflect in the displacement calculated by the processing unit. Although the displacement will not be obviously affected by a position offset caused by the noise when the displacement is relatively larger than the position offset, when the displacement is very small and is substantially identical to or just a little bit larger than the position offset, the locus can be disturbed to have a zigzag path.
For example referring to FIG. 1, it shows a schematic diagram of the locus outputted by a conventional optical mouse, wherein it is assumed that the optical mouse outputs the detected displacement with report rate of 125 times/second. For example, now a user slowly moves the optical mouse along an X direction. When there is no noise in the image frame, the optical mouse can output the locus of a straight line as shown by the dashed line. However, when there is noise in the image frame, such as +Δy noise existing at 16 ms and 56 ms and −Δy noise existing at 24 ms and 48 ms, the optical mouse will output the locus having a zigzag path. This zigzag locus can significantly affect the operation of a user in fine operation.
Accordingly, the present disclosure further provides an optical navigation device and a locus smoothing method thereof that can effectively eliminate or significantly reduce the zigzag locus outputted by a conventional optical mouse.